Gold(III) Compounds for Homogeneous Catalysis: Preparation, Reaction Conditions, and Scope of Application

There is currently a rapidly growing interest in the homogeneous catalysis of organic transformations by gold compounds. In a large number of specific studies, a wide variety of gold(I) and gold(III) complexes have been tested, and many of them have been shown to induce novel reactions or to exhibit significant advantages over conventional catalysts regarding rates and yields as well as regio- and stereoselectivity of reactions. Many of these catalysts have not been isolated and were rather prepared in situ from suitable precursor complexes, employing suitable solvents and optimized reaction conditions. While the knowledge about gold(I) catalysts has reached an advanced level, there is much less consistent information on gold(III) catalysts. In the present account, the preparation and properties of relevant gold(III) compounds and the reaction conditions for employing these compounds as homogeneous catalysts and catalyst precursors are reviewed. The synthetic chemist is introduced to the existing methods and thereby may be assisted in finding the most promising reagents and conditions that can be used in new synthetic strategies.